[Node.js Tutorials for Beginners] – Unit 3: Variables and Constants in Node.js

Table of Contents

1. Variables Definition in Node.js

2. Constants Definition in Node.js

3. Rule of naming variables and constants

1. Variables Definition in Node.js

Examples:

// use keyword: var

var a = “Nodejs Tutorial”

// not use keyword: var

b = “neoscorp.vn”

console.log(“Valiable a = ” + a)

console.log(“Valiable b = ” + b)

Ok, run: node unit3.js in terminal and see result:

Output:

Valiable a = Nodejs Tutorial

Valiable b = neoscorp.vn

2. Constants Definition in Node.js

Examples:

// constants difinition with data type is String

const c = “welcome to neoscorp.vn”;

// constants difinition with data type is Integer

const d = 10;

// constants definition with data type is Float

const e = 10.8;

// constants definition with data type is Logic(boolean)

const f = true;

console.log(“Constant c = ” + c);

console.log(“Constant d = ” + d);

console.log(“Constant e = ” + e);

console.log(“Constant f = ” + f);

Run: node unit3.js in terminal and see result:

Constant c = welcome to neoscorp.vn

Constant d = 10

Constant e = 10.8

Constant f = true

3. Rule of naming variables and constants

+ Variable and constant names must begin with a letter or an underscore character “_”.

+ Variable and Constant names are case-sensitive. For example, Name and name are two different variables.

+ Variable and constant names should not start with a numeral(0-9).

+ Name of variables and constants don’t contain speacial characters: !@#$%^&*()-

Note

Node.js is untyped language. This means that a Node.js variable can hold a value of any data type. Unlike nany other languages, you don’t have to tell Node.js during variable declaration what type of value the variable will hold. The value type of a variable can change during the execution of a program and Node.js takes care of it automatically.

Thank you!

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